fix(ci): cd web once in check step (cwd persists across commands)

.woodpecker/web.yaml

@@ -9,9 +9,10 @@ steps:
   check:
     image: node:25-alpine
     commands:
+      - cd web
       - npm install -g pnpm@10
-      - cd web && pnpm install --frozen-lockfile
-      - cd web && pnpm check
+      - pnpm install --frozen-lockfile
+      - pnpm check
 
   # Build and push immutable SHA-tagged image on main branch only.
   # See backend.yaml for the reproducible-build TODO.